Modern electronic devices inter alia comprise receivers that may have frequency-converting units such as a mixer. For setting up the receiver, a phase calibration of the receiver is necessary, in particular for frequency-converting measurements such as mixer measurements.
So far, a harmonic grid of several frequency points is generated that is used for phase calibration of the receiver, in particular the frequency-converting unit, also called frequency-converting device under test in the specific calibration procedure. For doing so, a base frequency is defined that is processed by division and pulse shaping in order to obtain a comb spectrum. The comb spectrum comprises several comb lines wherein all comb lines, namely equally spaced frequency lines, have a certain relationship to the base frequency defined previously.
However, the phase relationship of the receiver can only be calibrated for frequencies that correspond to the comb lines. For other frequencies, interpolations are necessary which result in higher measurement uncertainties.
Accordingly, there is a need for a possibility to calibrate a device under test in a more accurate manner.